SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ab4a8f1563ffc1ad6f0ca0a838ad39e58fa03760634cf3e9fd84c020a1da56b' 
  AND token = 'fg4AjzWncGGo9ApvvHyKVaj6ElbX6QK7nYHhJZpr/EM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}